Authorities in Lombardy, the Italian region worst affected by coronavirus, have introduced a law obliging citizens to wear face masks when they go outside, while Spain is considering recommending the public wear masks.

As the number of confirmed infections globally passed the 1.2m mark officials around the world appeared to be making a U-turn on whether the public should wear masks, despite huge shortages.

The calls came as a senior US health official braced the country for a coming week of deaths that would rival “9/11 or Pearl Harbor” in their impact on the nation’s psyche.

US surgeon general Jerome Adams warned: “This is going to be the hardest and the saddest week of most Americans lives, quite frankly.

“This is going to be our Pearl Harbor moment, our 9/11 moment, only it’s not going to be localised … It’s going to be happening all over the country. And I want America to understand that.”

Spain was mulling the new recommendation on masks as the country reported 674 new deaths from coronavirus, 135 fewer than in the previous 24 hours and its lowest number in 10 days. Infections rose by 5%, the smallest increase since the epidemic hit.

Italy also saw a significant decline in both deaths and the rate of increase of new cases on Sunday. The 525 new coronavirus deaths announced were the lowest in the last two weeks, and well down from the record high of 969 on 27 March.

The number of new confirmed cases increased by 2,972, a 3.3% rise compared to Saturday, but almost half the number of new cases recorded on 20 March.

Previously, countries had followed international health recommendations that suggested masks offered little protection and if not regularly replaced could increase the risk of infection.

More recently, however, following the example in some Asian countries, some experts have suggested that covering the nose and mouth may be useful in stopping the spread of the disease.

Lombardy’s president, Attilio Fontana, announcing the new law there, said people should “cover their mouths and noses” with a simple scarf, saying it would help “prevent you from spreading the virus if you happen to be a carrier”.

Images from cities including Rome, Naples, Milan and Turin showed an increase in the number of people venturing out in recent days in the good weather. The Lombardy law will be in place at least until 13 April, when Italy’s lockdown is due to expire.

On Friday Spain’s health minister, Salvador Illa, suggested the government would “probably” recommend the wearing of masks, though in many places they are almost impossible to find.

Protective masks – both the specialised air-tight versions required by healthcare workers and the more basic surgical versions – are in desperately short supply around the globe and have become the subject of bidding wars between countries. China is the world’s largest supplier.

The scramble for desperately needed medical equipment and protective gear has been most marked in the US, where it is causing intense squabbling between the states and federal government just as the nation is facing one of its gravest emergencies.

In New York, the worst hit state, governor Andrew Cuomo said in a press conference on Sunday that there had been 594 coronavirus deaths in New York state in the last day for a total of 4,159, but deaths had gone down from 630 a day prior.

“We could be either very near the apex or the apex could be a plateau and we could be on that plateau right now. We won’t know until you see the next few days,” he said.

At a time when Christians would normally be celebrating Palm Sunday, the pandemic continued to disrupt traditional observances. Pope Francis marked the day in St Peter’s Square without congregants, while in China grave-cleaning ceremonies were severely restricted.

Italy and Spain each expressed hope that their crises were peaking, though Italian officials said the emergency was far from over.

According to the Johns Hopkins University coronavirus tracker, the reported global death toll neared 65,000 as outbreaks of the disease continued to flare up, including in Tokyo, which recorded a record daily increase in infections at 130.

An International Organisation for Migration official in the Malakasa migrant camp in Greece. Photograph: Alkis Konstantinidis/Reuters

The number of people infected in the US soared to more than 300,000 as deaths climbed past 8,500. Many of the victims are in New York City but the outbreak is deepening elsewhere too.

Greece moved to quarantine a second migrant facility after a 53-year-old man tested positive, the migration ministry said on Sunday.

The Afghan man lives with his family at the Malakasa camp along with hundreds of other migrants and asylum seekers. On Thursday authorities quarantined the Ritsona camp in central Greece after 20 asylum seekers tested positive for coronavirus. It was the first such facility in the country to be hit since the outbreak of the disease.

In China the spread of the disease has largely subsided but officials have been cautious about reopening public spaces.